I think you did the BLTOUCH a disservice, Tom. While the other sensors perform equally well in any position, such as your horizontal position in the test fixture, the BLTOUCH is designed to work vertically. When put in the horizontal position, the sensor pin and magnet must overcome the additional friction of sliding along the bore of the guiding hole. This can lead to inconsistent measurements due to friction and grabbing. I consistently get average variation in readings around 0.015 mm
This!. The BLtouch is probably the best sensor on the market when used properly. It doesn't care what your build surface is and once your offset is determined you never have to worry about bed leveling or adjusting anything to do with the Z axis again. I routinely start a print and walk away, and expect it to come out perfect, and it does. The autoleveling is done once the bed is up to temperature, then the nozzle wipes across a brass brush, and quickly moves to the bed and starts printing. The BLTouch is an awesome bit of kit.
I want to address something I've been seeing floating around the internet regarding the inductive/capacitive probes. People keep saying you need a 12 V to 5V voltage divider on the output. This is partially wrong, and may, in fact, introduce more errors in your bed leveling. The sensors do absolutely need to be run from 12 volts to achieve their rated specs, but if you are careful to buy an NPN type sensor, you can simply plug the output directly into the Ramps input pin. This sensors are what is called "open collector drain" output. It means that it doesn't provide an output voltage when trigged, rather it pulls the signal provided to it to ground. The Arduino/Ramps board has internal 20 kohm pull up resistors on all of its pins (enabled in Configurations.h). This pull up provides 5 volts to the output pin of the sensor, when the sensor triggers, it pulls that 5 volt signal to ground. If you use a voltage divider, you might reduce the 5 volts enough to cause unreliable switching in the Arduino. PNP type = needs voltage divider. NPN type = do not use voltage divider.
+Thomas Sanladerer Great video! Aluminum tape definitely works though! I have used it multiple times, amd we also use it reliably at our Makerspace. There are different types of aluminum tape however. It looks like you are using the "metalized" type that is similar to Mylar. That stuff will not work. You need actual aluminum tape. The metalized type isn't very conductive. Actual Aluminum tape is basically just like aluminum foil with an adhesive backing. The only thing you have to watch out for is the adhesive. Alot of aluminum tape has a low temp adhesive and will start peeling up at around 50°C, but you can find some that has a high temp adhesive which is what we use under our PEI at the Maker Space.
You can tell by the video that it's the wrong kind of aluminum tape. Actual aluminum tape has a dull surface to it, and it is much thicker as well. Basically the tape you tested is just plastic tape with a small ammount of aluminum vapor deposited on the surface. Other than that, Great video!
Had minor problems with some Aluminum tapes and inductive sensors due to reduced sensing distances that I didn't like quite as well, found copper tape to be far better. But either works great. In fact on my setup(8mm inductive @12v) copper has better sensing distance than the aluminum heatbed(My printer crashes on autolevel if I leave the glass off and it tries to sense the aluminum sheet) Those here who use copper/aluminium tape under 3 or 4mm glass: What is your sensing distance? I put the tape on top and just don't print in the very corners as 1mm or so above the glass is too close for me with the tape under it.
I've been using a piece of heavy duty aluminum foil between my heated bed and glass for almost a year - with a 8mm inductive sensor it works great. It worked with a 4mm sensor as well - but was a bit too close for my tastes and Marlin's probe test seemed to show the 8mm was about the same for accuracy so I've stuck with it and been very happy.
I think one of the things you have to remember is that the BLTouch is an all-in-one solution for bed leveling; it won’t interfere with your nozzle at all because of its retraction. That retraction most likely adds a significant wobble.
If the tests were conducted as in the video , what do you make of Antcap's instructions regarding how the BLTouch must be mounted ? The manufacturer's website for the BLTouch clearly states this: if the sensor is mounted horizontally it WILL give wrong results. They don't equivocate. It is a crystal clear stipulation. It is underlined even . Would you care to comment ?
@@Traitorman..Proverbs26.11 except it is not just an electronic device . It is an electromechanical device and it is purpose designed to work mounted vertically . My kettle is a simple electronic device , it won't work as intended if I run it on its side or upside down.
@@Traitorman..Proverbs26.11 i take your point . But my inquiry is more to do with the method used to derive a conclusion , rather than the merits of this or any other device evaluated in the test. Manufacturer says this device X is designed and only works when used using method Y . Testing is done using method K , results turn out to be suboptimal . Why are the results suboptimal ? In truth we don't know ,. It may well be the product is unreliable but testing by using method K is not the way to find out. Over and out.
If I'd design a device like this small I'd surely factor the gravity whether I'd use a spring to push the pin out or not (as it happens I'm not a flat-earther, I "believe" in gravity). Probably the pin is pulled in by a coil (with the ferromagnetic pin acting as a core). Because it needs precision, the spring, if there is one, should be weak, but the trigger point will be more influenced by the sensor orientation. I guess you could make it switch just by shaking it in the hand. To be able to ignore the gravity direction (and to have repeatability no matter the sensor orientation), the spring should be stronger, but, in this case, the precision will go away, especially with microsteppping. Factor in the uneven friction, which can be significant for a such small device and the need to keep the price small and you'll have an answer. I don't own this small guy (BLTouch) and I didn't check the datasheet, but your observation is perfectly valid. And the BLTouch test is not valid.
Also the other mechanical sensor results aren't valid either because he's just testing the switch itself when to actually use it you'd need a mechanism to remove it to actually print.
When I was working on the auto-alignment at Type A Machines, I was very surprised at the unsolvable nature of the auto-alignment problem. There's essentially no way to get the desired flatness when combining the standard deviation of the sensor, with the rated flatness of aluminum, and the thermal expansion when heating to over 80C. You could conceivably do it with steel, but that has other challenges from the weight and cost of facing. Glass is really the only material we could find with below +/- 50 um flatness and dimensional stability when heated (we even managed to find some with +/- 0.3 um). Really the solution is to crowd source some magnetic glass, minimum order is 5 tons and works with induction.
I know this video is over a year old at this point so I hope this is still relevant. He tested all of these sensors horizontally. The BLTouch specifically states NOT to use it that way. It needs to be hung vertically as it would be mounted on a printer. I've used a mechanical switch with manual leveling, a mechanical switch that flips up with a servo, capacitive sensors, inductive sensors, glass beds, PEI sheets, Zebra Plate from PRINTinZ, aluminum beds, and even tool steel beds. I've tried a total of 15 different sensors and 11 different beds in my few years of 3D printing. NONE of them were as accurate as simply using the BLTouch. When it is installed correctly, it just works flawlessly. Best of all it doesn't care one bit what surface you have, it will work on anything. I think it deserves a re-test.
It has almost no deviation on his tests, maybe 3 micron, which is next to nothing. He also states that it doesn't care about the surface material. So actually even in this horizontal test it comes out as (one of) the best choices regardless of where you want to print on.
I never thought about using such sensors for measuring the bed level. At work I use mostly inductive ones but just for checking if there is an object or not. When I saw your video about the Prusa i3MK3 and its autoleveling I had doubts about the precision, but your video here has told me better. Thank you.
Tom. You pretty much nailed this one....also you mentioned that capacitive sensors are thrown off by humidity...they are actually the instrument they use to sense humidity.
I would love to see this video updated to include Ultrasonic sensors, and name brand inductance sensors like those made by Osram up to say 16mm sensing distance. That being said, this video is so helpful. Thank you for making it.
ultrasonic too hard to work at small distance, basically time of flight is sooooo short electronics is not fast enough to process it. if you have at least 10cm distance then there is enough time to do calculation at reasonable precision yet you need to run higher frequencies. We tried to do auto focus device at 25mm distance even there we had to give up on ultrasonic sensors.
I don't know where you're getting your sensors but I use 1 strip of aluminum tape under glass. Works like a charm. I used it as a retrofit onto the printrbot simple metal and it worked better than with the aluminum bed.
1) 2) there must be distance for both of them. None of them will allow you to notice when the nozzle < 1cm. I guess there might be a workaround with offsets though when 5/10 centimeter or something like that.
Lidar is a process where an infared laser light creates a kind of radar around it. 3d Printers are only trying to measure distance in one direction. It is much simpliler and more practical to not use lidar. Ultrasonics are another radar type with help of a servo, Most radar like sensors are kind of inacurate but still acurate enoguh for their use cases like on a car or a plane. Where 3d printers are looking for accuracies of up to micrometers. Always learning, Aidan Villacampa
I feel like I've been in a time capsule. I got an early MakerBot CNC (#180) in 2009-ish, and was printing 3mm ABS on a raft on Kapton tape, using a .37mm layer height and no fans or heated beds. I woke up in 2021 receiving a Prusa Mini+ that prints directly on a magnetically attached and heated bed, using 50 micron layer height if I so desire, and supporting PLA, PETG and a plethora of other materials out of the box. In the old times, I tried using an optical mouse sensor for auto-leveling using focus. It actually worked with the sensor 1 mm from the bed, but I wanted something more like 10mm from the bed and never got the optics to work correctly. The idea was that the optical mouse sensor not only sensed the height, but also could read markings on the bed, or a printed sheet attached to it both for calibration precision and for communicating what to print. I never got to finish this project, but it seems like it still might be worth while: the inductive SuperPINDA doesn't even provide much headroom. Does anybody here have experience using optical focusing for Z height calibration?
You measured mostly repeatability, and mostly ignored system accuracy due to heating/cooling. Excellent video, great charts. Should have had an external digital DTI measure the setups actual position, logging, and dwelled (paused) after contact on the probe. Then the DTI log would show where the moving piece actually was at probe contact, vs the start position when all was cold. Likewise, the triggering circuit for probe hit is critical. I did a lot of work on this, 8 years ago, on testing for lathe spindle index sensors, and we proved conclusively that sensors will give very fuzzy signals, that vary with temp/speed/luck. A sharp triggering circuit, and a sensor tuned to give a crisp response, will be about 100x more accurate on a range of speeds vs a typical probe "hit". I also saw that optical sensors will repeat to about 2 microns, with very simple basic cheap sensors.
Thanks for your videos. I have experienced difficulties with sensors. After a few consecutive prints, the levelling of the bed was not accurate, but was accurate again the day after. I now make the levelling when the bed is hot, but the problem still exists. I believe that the sensor close to the bed and the head warms up little by little, and the temperature of the sensor may have some effect of the measurement.
I have a question about the inductive sensors... How much 'material' do they need below and around them and at what point does it make a difference? For instance: If I trigger right on the edge of my aluminium plate it triggers lower then when probed in the middle of my plate. Does thickness play a huge role? Do they trigger higher when there is a bearing holder right below the sensing point? How thick does the aluminium need to be to not have that influence...
one thing you're missing are FSRs, force sensing resistors. i use them on my delta which has a glass bed over an aluminum heat spreader. they seem to be very repeatable but only above 0.13mm deviation, any less than that and smoothieware's autocalibration gets upset
How do you feel about auto levelling? I personally don't like the idea of the Z axis having to move during a layer print. If I'm worried I just use a raft, which will end up levelling before the actual model prints. What I really want to see is 3 servos to level the bed corners.
HenryLoenwind no idea what crazy setup you're envisioning but I guess it's not the one I was... I use servo in its loosest term: any motor hooked up to a potentiometer to increase positional accuracy, not as in your hobby king swivel arm 180° ones. As such, a small motor attached to the thumbscrew so it works as a linear actuator and a linear potentiometer hooked to that setup for positional feedback. Doesn't seem too ludicrous. You were suggesting using the nozzle to turn a thumbscrew? That grates against my engineering sensibilities quite badly.
+HenryLoenwind Oh man, the mental image you just gave me of a printer spinning its nozzle around a hooked screw to 'adjust' itself before it feels comfortable enough to start producing a part is hilarious to me, for some reason.
My team is actually working on a printer for the market with all best stuff available, and that includes 3 steppers for Z axis for REAL bed leveling, not some sort of lame workaround. ;) Fast hotbed (0-110C in 25 seconds), 300x300x450 build volume. Won't be cheap though. Good stuff is never cheap :)
Usually there is a spec sheet prescribing optimal materials and thickness with respect to frequency (typically a few mils for ferrous and 2-10x thicker for nonferrous). The relevant parameters are permeability and resistivity of the material. Ferrous materials and sensors generally can give higher resolution with larger sensors, and non-ferrous gives better resolution with very small sensors (even though typically smaller sensors give a shorter range), but there are universal sensors that have an equal correction factor for either. Generally ferrous sensors would probably work best in this application, and Generally target size should be 1-3 times the sensor diameter. Also, in terms of layered copper/alum tape, remember that you are isolating the layers electrically, so the induced eddy currents will be smaller (just like transformer laminations)… meaning you may need more layers of tape than you would expect. If I were adding a proximity sensor after the fact, I would get a medium-distance ferrous sensor, tape ~1mm thick steel disks to the bottom of the bed at the sensor points, fiddle with the distance, and call it a day.
Another one to try is the piezo force sensor. Mount it in your bed support or (as I did) in your hot-end mount on the carriage and it registers contact of the nozzle to the bed. Zero probe offsets in X, Y and Z, change nozzle and all you have to do is run the auto-level. Super convenient. Precision Piezo do a good rig.
This is interesting. I see that microswitch w/o lever SD is about 1 um. Same as for inductive sensors. What is the point of using Bl touch or inductiv sensors if once can just put a microswitch button down on the print head and do autoleveling with it? but how to put it higher that the nozzle...
For the mini-IR probe to be used on glass, the instructions say to put a black matte backing (black paper) behind it, or to paint the surface behind it matte black with high temp BBQ paint. A reflective surface behind it like aluminum will give the kind of results you saw in your tests.
Tony, see my clone of Davids mini IR, community.robo3d.com/index.php?threads/differential-ir-height-sensor-attemptin-clone-aint-sure-of-success-now-stage-10.6601/ ............Yes, you correct.....paint back of glass flat black.......Jimmy
Thanks for all that testing but now I want to know which probe is best for the Scoovo X9H. It has Kapton tape directly stuck on a glass bed with the silicon heating pad just under it. Board: RAMBo Firmware: Marlin
What would the point be? He flat out told you it was done sideways to remove backlash from the equation and limit the results to just the component . Turning them upright wont change how the devices reacted mechanically one bit .
@@wind5250 and apparently you didn't read the instructions for the bill touch it supposed to be vertically standing not horizontally to work properlyso if you want to test something the way it was made to be tested and used that's the way you do it not for non-science a backlash there's no backlash when there's up and down
@@mathewphillips4185 not only did i read the instructions i own one. Laying it on it's side is just as valid as standing it up. The fact his results are within spec as well as repeatable , and comparable to other reviews more than demonstrates this .
@@wind5250 you read the instructions but apparently didn't follow them (and are misusing the equipment you own, but that's your choice). It's simple physics to demonstrate that there is a mechanical difference in how the probe behaves when it is vertical vs. horizontal: When vertical, gravity acts on the spring to pull it down and keep it in its rest position. When the probe hits the surface, it can cleanly move upward until it can trigger its Hall sensor. When horizontal, not only is gravity no longer aligning the spring correctly, but there is additional friction resisting the movement of the probe (thus causing the probe to move fractionally less for the same amount of deflection). When the probe contacts a surface horizontally, there is no force preventing the probe from deflecting sideways ten+ microns before triggering the Hall sensor, leading to a loss of precision. If using your equipment like this works for you, that's great, but it's objectively incorrect to say that orientation doesn't have an effect on the BLTouch and other precision equipment.
@@TROPtastic You took all that time to write a reply but obviously not enough to actually comprehend before hand . First of all i never said how i mounted the device let alone i mounted it sideways. What i said was it would make no difference to repeat the test upright because the results are within spec and repeatable which they are . You are literally arguing that the device will perform better than the manufactures tell you it will by turning it right side up. Anyone who actually uses this device knows they give invalid readings after time the only valid questions would be what version this is and was this one new or used .
@@chloemcholoe3280 The glass (print bed) will be a flat piece of glass. However, it is then mounted inside a mechanical device. If one edge is mounted lower than the opposite edge then your first layer of 3d printing will not adhere well to the glass. The print bed must be leveled to ensure that the 3d print head glides over the whole print bed at the same height before a 3d print begins. Then the 3d printer will reliably 3d print the first layer and subsequent layers. This leveling can be done manually, with no automated sensors, or leveling can be done with automation using the kinds of sensors tested.
@@paull1316 yeah. my point was the reason I for these probes in my opinion is for fixing warpage. with glass you can just like live adjust the 4 corners as it's printing and it takes a few seconds really
@@chloemcholoe3280 - glass can be warped or bowed if not made correclty. Also, glass isn't the only height variable. its possible that the gantry rail that the hot end rides on can be bowed.. which may change the height of the nozzle as it moves back and forth.
Informative as always. I use a LJ12A-4-Z/BY with an LM7805 VR on the output this gives a steady 5 volt trigger signal. If you increase the input voltage does it does it strengthen the sensing distance.
This is awesome! Also fun fact: I use an aluminum mk3 heatbed with a 3/32 inch (2.38 mm) sheet of glass AND blue tape. The 8 mm inductive sensor triggers just fine for me thankfully.
Great info, thanks Tom. I recently installed David Crocker’s IR sensor on my Prusa i3 box frame, which uses a 3mm glass bed and a red Mk2 PCB heated bed, inked black with a permanent marker in the sensor probing areas. After watching your video, I tweaked Marlin so that G30 would output the trigger height to 3 decimal places (1 micron resolution). I turned on my printer and made 46 measurements with G30 and got an s.d. of 1.4 microns. I noticed a trend in the data, presumably due to temperature drift somewhere in the system (probably the steppers warming up my crappy M5 threaded rods so the trigger point appeared to get lower with time). So I did another 34 measurements and the s.d. was 0.8 microns, but still with an obvious trend. I think these numbers are an order of magnitude better than you got with glass. Maybe it matters what is behind the glass? I should also mention there was a thin layer of glue stick on the bed under the probing area from the last print. Also I have slightly modded my sensor board to increase the trigger height from about 2.7 mm to 3.2 mm by tweaking the angle of the outer LED using a hot-air rework station. This is so that it would clear the bulldog clips I use to hold the glass down so I could still retain my full 200x200 build area.
That's because, most likely, your bed surface is suitable for Crocker's IR sensor. The testing surfaces and setup in the video is stated as not suitable in the documentation. If you are running a glass plate on top of bare aluminum it is recommended to paint the aluminum matte black. I wish this test was done with the proper setup.
I don't use autolevel for couple reasons - I print on glass, and I can't afford (or justify the expense of) ball screws. I use an inductive sensor (LJ8A3-2-Z/BX-5V), as a fixed Z end stop switch, sensing a mild steel bolt head. Using a digital 'dial' gauge, I get repeatabilty of ~3µm delta (not standard deviation). That's with T8 lead screws and DRV8825 drivers, 32 microsteps, so 1.25µm per step. Not bad I think, for a modest outlay, and plenty good enough for 3d printing.
Mh for the LJ18A3-8-Z/BX I run it directly from the board without a voltage divider. Tried it first with your voltage divider approach but then the sensor didn't trigger at all. But running the sensor directly of the board it works fine (for me on a aluminum bed with BuildTak ^^)
Try the sharp with an offset. Ultrasonic sensors generally can't read values accurately below a certain valve, due to the reading times required for the sound wave. Try offsetting it and see if accuracy is better.
Hi, I use some lj12a3-4-z/bx on my printers and it triger on a glass plate with some almuminium foil sticked with rubber tape on it. Also supplied in 5V directly plug on my borads without any led or resistor.
I have Omkon SN04-N inductive sensor. I use glass bed and have one layer of aluminum tape ON TOP of the glass where the sensor probes. It works pretty well :)
I'm using an 8mm NPN output inductive probe, the same 8mm one in the video. Rather than using a voltage divider what I use is a diode instead. When off it puts out 12V and goes low on trigger. So you put the diode in series with the output with the cathode towards the probe to block it and make sure the pullup resistor on the input is enabled in the firmware. When the probe triggers it goes low and turns on the diode and pulls the input down to .6V which is good enough to be considered a low on the input. The diode will give a nice cleaner trigger to the input than a resistive voltage divider will and it's easier to wire and insulate, just solder in series and cover with heatshrink I'm sensing nothing but a 10"x10" PCB heater (Sitting on cork to keep it flat and insulate it) with a 2mm thick piece of hardware store glass on top and the repeatability is near 100%. I always use it on a preheated bed and that seems to help repeatability. My only gripe is you have to recalibrate it in the firmware if you do any work on the hotend or X carriage but that's not often so it not a big deal since the rest of the time it's pretty much "plug and play" printing. Cheap effective upgrade IMO
I liked this video a lot, I simply wish the sensor I use (David Crockers IR Sensor) had a slightly deeper/more in depth review. I am given more confidence to continue using it, however, will no longer calibrate it with the heated bed on. That is a variable I had not even thought twice of! I simply set the bed for 55° for my PolyMax PLA and calibrated it when it was done heating right before the print...Thank You for that!
for my scratch built reprap delta we used a simple conductive type, running 1 wire to the nozzle, and another to the aluminium bed, reeally simple and easy, and no need to worry about effector tilt
Would you please make a video explaining limitations of autoleveling? A lot of people seem to think it will compensate for misaligned axes (like when a dual motor Z axis loses motor sync and the X axis tilts).
@Thomas - And additional info for you: I've noticed a huge unreliabilty with my inductive sensor C-Lin P-802N (runs nicely at 5V) - first I thought it was caused by temperature differences caused by my huge high powered heat bed, but after a while I found that even smallest drops in the voltage of the printer control boards PSU makes sensing distance very unreliable (using a cheap chinese 12V 6A notebook-psu brick for the board+hotend). I've came to that conclusion after changing to a old and dirt cheap ATX psu as reliability got MUCH better but still got not perfect (bad quality "250W" ATX PSU). Now I'm using a 200W 12V halogen trafo, rectifier, added several very huge Elko capacitors (about 50k µF all together) and now sensing distance is +- 0.00Xmm reliable instead of +-~0.3mm!!! I heard that the BLTouch (and it's chines "3DTouch" clone) have similar problems.
After re-viewing this video again, I wondered why you tested all of the sensors on the same surface (aluminum) as the different types of sensors each work best on particular surfaces. For example the inductive sensors only work against a metal build surface such as flex sheets with PEI or PEX. The IR sensors work best with a black body, or no- reflective surface such as build tak, and poorly against aluminum and non etched glass. Capacitance probes need to be adjusted, but will work with numerous surfaces. They should perhaps be used with the bed heater on, and at less than 65C.
That test machine was brilliant! I built an i3 clone following your guide and this sort of thing is really great for developing upgrades. Thanks for being so thoughtful in the design and execution of the testing.
When you tested the inductive sensors you didn't take in account the heterogeneity of an aluminium bed. While printing with my VORON I have experienced inconsistencies with inductive sensors and my PEI-painted Aluminium bed from Clever3D. Basically the trigger distance was consistent on the same spot (just like in your tests), but varied when probing a different spot... and you need to probe at least 3 distant spots. Today I switched to the VORON 1.5 X carriage, which uses the hotend itself (mounted on a mechanical microswitch) as a probe and the situation is vastly improved because a microswitch isn't affected by materials and temperature. EDIT: In theory this applies to IR probes too, as reflectivity may vary across the bed.
Seeing as inductive probes can see through plastic/silicone, would it be sensible to put a silicone sock (or even a printed plastic cap) over the bottom of the inductive probe to reduce temperature effects? I'd be really interested to see if that helps.
How does Marlin deal with the measurements from the probe? Will it compute a plane with minimum distance to each point, or does it compute a non planar surface to deal with deformations of the bed or bending/wear of the linear supports carrying the print head.
The video was very informative. But I have to question your method of testing the inductive probes. The aluminum bed on printers with them are only around 6mm, not the large mass of aluminum you used. Could you rerun the tests using a 6mm aluminum plate and test the trigger height between probing the center, edge, and corner of the plate? In my use of an inductive probe, I have seen a difference in trigger height based on where the probe point is on the bed.
Edward Boston I may be crazy, but my inductive probe acted like it was "seeing" my steel bed carrier through my MK3 aluminum heated bed. Is that possible?
I doubt it, but you never know. I was seeing all sorts of inconsistency with the probe I was using that I gave up on it and went with a BL Touch. One issue I had was I have a PrintBite on my bed and with a 4mm probe, it had to be so close to the bed that it was almost at the same level as the nozzle.
Almost 2 years later now and I still adore my BLTouch. Even if it statistically or scientifically isn't the most accurate out there, as you say, it's 'more than good enough'. It's so rare to have a calibration fail.
Tom, you really should continue wit the Myth-busting line. I have been experimenting with sensors I have to say that your conclusions corroborate my experience 100%. Given mechanical switches with lever , although less precise than inductive, can be used with borosilicate glass, I will stick to those. Awesome video, congrats.
Tom, if you retest the optical sensors, I would like to see it done with different color materials behind the glass (specifically black, white, red and peach- the common colors of heaters). Would also like to see how ambient IR light affects the repeatability, i.e. fluorescent lighting and sunlight. I had very mixed results with David Crocker's IR sensor during probing with sunlight coming in through the windows, for example, vs. probing in a dark room.
The IR sensor I make doesn't like bright sunlight (no clouds in front of the sun) shining directly on the bed and reflecting into the sensor. The current version 1.2 will flash the LED rapidly to warn you when it detects that. Otherwise, it isn't affected by ambient light. Incandescent light - especially halogen - affects some other types of IR sensor, but not mine. I'd also like to know what material was behind the glass when Tom did his tests. The reason that glass and other transparent materials can cause problems for optical sensors is that you get 2 or 3 reflections: one from the front, one from the back, and possibly a third from whatever is behind the glass. We want the one from the front to be stronger than the others, which is why we recommend a black surface behind the glass.
Have you try the membrane film based zprobe (basically just like a membrane keyboard/contact switch)? I find it is the best zprobe for delta printer as it can be easily mounted directly under the nozzle to give the best on-points reading that a delta auto calibration needs (no zprobe offsets), without being affected by heavy trigger force that could potentially deform the belts/pivot points etc.
Runder Caster go to microcenter! they have a Prusa clone from wanhoa for $299! works amazing for the price with decent print volume 200*200*180. I'm trying hard not to buy a second one.
Building printer your self is much cheaper and you will learn how it works, so when something breaks you know what to replace I already ordered all of parts required to build clone of prusa for around 80$(not including frame, I will build it my self)
woops sorry misread your post as "get a 3D printer" $299 ($399 online elsewhere) was the cheapest I'd seen for fully assembled all-metal printer with that build volume just trying to help out.
Enjoyed the video. I've actually used the thicker gauge of "Duct Repair Foil tape" by sticking it to the top of the glass sheet and then putting a sheet of BuildTak on top. Maybe that's not aluminium? Anyway, my cheap sensor saw it.
I'd be interested in your review of the piezo electric z level sensor, it looks super interesting to me. It has a bed option and a hotend option, it's always there and has no XY offsets.
How are you only at 67K subscribers? Your videos are so good and the editing lighting etc is amazing! I wish you lots of success Thomas. I really enjoy every single video that you make.
Tom's videos are great and have amazing production value but how many 3D printer enthusiasts do you think are in the world? I imagine 67k people is a sizeable proportion of them.
Touché, but also lots of people that are interested in 3d printing don't have to be enthusiasts. Like you said though his production quality is probably some of the best on RUclips, and that is not an exageration. Many channels 10 hell even 100 times his size can learn a thing or two from him!
67k is quite a small subsection of 3d printing enthusiasts. Talk to Lulzbot and Ultimaker about their sale figures. Heck, Prusa and his company are shipping 3,000 printers a month, and that's only because that is the limit at what they can produce right now, giving new orders a 7 week lead time.
So this got me thinking what is the size of the global hobby 3d printing market? There's plenty of data on additive manufacturing market size but that's not people buying prusa i3 mkII's.
Your videos are all excellent, but this one is superb! We spent so much effort learning this on our own... at Kikai Labs we use a capacitive sensor, take 16 measurements prior to starting each print job and level the bed automatically. It works great. We do calibrate the sensor first using three different bed temperatures, as it does matter as you pointed out. Interesting observation about the humidity, though... I used capacitive so that it would measure the glass surface, and we use a mirror instead of plain glass, and get better results. Also we found that the smallest the measuring distance, the more accurate it is, so we measure from 2mm away using a 12mm sensor.
You should have tried steel foil. I bought some SS foil off ebay, a single layer of fractional mm thick tape does trigger a 12mm inductive sensor, but NOT though glass. Maybe on top of glass covered with kapton tape?
Wondering if instead of aluminum tape, if using a quarter or half a zinc coated, or stainless steel washer, sanded flat and to a common thickness, and glued to "sensor points" on the corners, or a known distance from a corner, would be a workable solution for glass build plates and inductive sensors. One might have to go to a fender washer for enough ferrous material to sense, but if there is a way to tell Cura or your slicer that those locations are off limits for printing, it might be workable. The advantage I see is that most of us have access to washers, if you've adjusted an inductive sensor for an aluminum bed, you may be familiar with having to do other physical adjustments already. Down side would be that you wouldn't want to do grid leveling for this, unless you could etch your glass to drop such washers into the surface, and I'm not thinking that's a great idea. Unknown is how large a washer you would have to use to get reliable results from an inductive sensor.
great video! cool rig, shows the power of rapid prototyping. been thinking about Auto leveling, I have a delta that uses pressure pads, would be great to see how well it stacks up, down side is Auto leveling is tapping printer head into the bed every time.
Wow love the detail and different perspectives covered in this video. I'm a sucker for this sort of data. If inductive sensors have their detection range halved, and there is a sheet of window glass (2.38mm thick) on top of the bed, doesn't that mean that both 2mm and 4mm inductive sensors are right out? I'd love to print ABS right on the aluminum but nothing sticks to it without a carefully maintained pile of glop (glue/slurry), where glass works for weeks with a single light hairspray application.
I wish your test apparatus also used a layer of glass, typically found on CR-10x's. If the sensor needs to be too close to the glass so as to interfere with prints during printing, then that is a fail. Please account for sensing distance to the detected object.
Have you looked at a sonic sensor? Like the ones that come in the Arduino kits. Can it be adapted to measure and trigger at the distance it is mounted, at on the print head? When I played with one some time ago, It seemed very accurate for 50mm to 800mm.
The BLTouch manual specifically states the sensor must be run vertically. Since your test rig is horizontal, the results are suspect. It would be good to rerun the BLTouch test with it held vertically.
Many years later and the BLTouch and the clones are the most used. Inductive requires the metal to be the exact same accross the entire bed surface, so it's out in most cases. Of course now we have Lidar sensors. Sticking with my genuine BLTouch setups for now. They just work.
Here's a question, with the inductive sensor, does the voltage range matter? ie does the sensor (say, a 6-36v sensor) work the same at 6v, as it does at 36v?
The Sharp detectors take 16.5 mSec to take a measurement and output that value. Or put another way, the analog or digital output changes every 16.5 milli second and the output stays the same in-between its readings.
Thanks for your video, now I can comfortably purchase an induction sensor with the knowledge I will likely have to give up my glass bed. I appreciate all the testing you did!
Great, informative videos. Thank you. I was wondering if you tested the BLTouch horizontally or vertically? I think that its accuracy is affected by gravity and would benefit from a vertical test. I agree that it is a good alternative for glass probing.
@@pellin-unleashthebiker3101 not when you're dealing with micron-level precision. I calibrate measurement equipment to this level as part of my job, and misusing equipment like this is a total non-starter if I want something to perform accurately.
@@TROPtastic did you look at the precision of the bltouch horizontally in this video? It is only some microns, so still perfect. So the conclusion is it really does not matter in this case. For something else it may, but not for a simple 3d printer.
FYI, you tested the BLTouch in the wrong orientation. I tested mine thoroughly at multiple homing speeds and standard deviation was 0.01mm with the occasional one that that was +/- 0.02mm, on all but really fast homing speeds. I now do a two step homing with it, once at 1500mm/m, and then a slow home at 100mm/m from ~2mm of the bed.
For the longest time, when I was running my Simple Metal with a glass build plate, I had to use aluminum tape to get the inductive probe to fire. I assure you it 100% worked. There are different thicknesses of aluminum tape, I suspect that was your problem here.
Hello. Where can we read the results please? I am very interested by mecanical switch results (with and without lever) As I understand, at 7:24; mecanical without lever is more precise than BLTouch ? cool!!
The only reason I moved from an inductive sensor to David Crocker's IR sensor is because of the bed. If the thickness of the bed varies, or there are holes in it to reduce weight, the induction sensor will trigger at a different height to more/less material being on the bed in one location.
Awesome test! Very methodical tests. I have the cap sense and have noticed the heat issues. I think I'll switch to inductive. I would like to try a glass bed over the aluminum lower plate. I wonder if the the longer range inductive sensor would be practical at detecting the aluminum glass combo.
Great video Tom. I have two related questions. Since you agree that 12V is far more precise than 5V would 30V be even better? And if so can you use an external power supply to power the sensor and feed the result into the board without damaging it?
Your idea seems correct, but no need for an external power supply, you could use a "step up" www.amazon.com/Solu-Adjustable-Converter-3-5-35v-Voltage/dp/B00VA0GRFG/ref=sr_1_3?ie=UTF8&qid=1490647751&sr=8-3&keywords=Step%2Bup%2B5%2Bto%2B36V&th=1 And then divide the reading with capacitors
Cool comparison. I was looking for a sensor to measure distance for my research project. So this helped me to understand the basics of the sensors. Thank you for that. Also is it possible to have the part list for your test setup? It will be really useful.
I know this is an old video, but I hope that you still read comments. Tom, How do you connect a simple 2-wire switch to the mobo for the board to know when it has closed the circuit? A quick vid would be nice.
The exact procedure really depends on the firmware used, but the steps are typically: Configure the pin you want to use as an input in your firmware Enable pull-up for the pin in software or add a physical 10k resistor from the microcontroller's positive supply (3.3V or 5V) to the pin Connect one pole of the switch to the input pin, and the other to ground. This way, the input pin will be high as long as it's not pressed and low when pressed.
prusa's pindais always the smallest of the group :D. Hey Tom how about plastic cube inductive senders? SN04-4, TL-Q5MC1. They become quite popular due to a low price and compact size. I've tried them but they seem to have a higher temperature deviation compared to round metal variants.
Re-viewed this video. It occurred to me that an NPN NO sensor has an open collector output to ground (V-). So it might be possible to run the sensor at 12-24vdc power, but have the output switch a 5v pull up resistor to ground thus giving a 5v negative true logic output. OR it could switch an opto isolator. Either way, you get a 5v logic output, but might need to invert the logic in software. Marlin probably provides for this anyway.
How do i use a microswitch for the auto leveling? I mean where should i put it, so it is not interfering with the nozzle and mess up the print? It seems a good option for me. I have glass bed on top of an aluminum sheet... (DIY)
Why don't they sell a piezo or ruby sensor? I mean the proffesional CNC machines use Ruby tips with light refraction for sensing, and the price of synthetic ruby is actually quite affordable. The piezzo idea is to just to let it act like a microphone hearing when it hits the surface.
would it not be best to combine different sensor types in one device, for example inductive and contact, and measure the deviation of these for error analyses?
How about a extruder comparison test? or better, how about a linear bearing comparison test? I am not a huge fan of Prusa's linear bearings but would love to know some numbers of if Igus or others are really better.
Some time ago I built a DIY heated bed to my Printrbot Simple Metal. In order to get the sensor to detect the bed through the glass, I had to put a sheet of 1 mm galvanised steel sheet under it. But now, the sensor almost touches the surface of 3mm thick borosilicate glass. Not really useable. I could not find borosilicate glass less than 3 mm thick. I read that plain glass can withstand a certain amount of heating and cooling as long as it happens slowly. But how slowly? I decided that glass of the type used in picture frames was cheap enough for an experiment and I bought a couple of 200mm square glass frames from a bargain store. This glass, being only 1.5 mm works reliably with the built-in heating setting (I did not have to make the glass heat more slowly) though I must warn that, since I only use PLA, this setup has never been tested above 60c! Also, borosilicate glass can withstand some downward pressure (when things go slightly wrong) - but picture frame glass cracks immediately. I lost both in the experiment, but have had 6 perfect prints off the third, with one coat of Magigoo on the glass.
Necro, but thanks a billion for making this video. Would be interested to see what new sensors are out there, and learning more about the LIDAR from the Bambu Lab X1C
Assuming the data collected is accurate, in order to make probe comparisons, large tolerances must be added to inductive probes that include the build plate tolerance stack for non-conductive top sheets (adhesive, PEI, etc...) . Also the BL Touch is intended to operate vertically, more friction is introduced horizontally. Once all this is considered and included, the BL Touch will compare MUCH better, if not the best. Also, if tossing on a thick G10 build plate for printing Nylon ... only the BL Touch or a micro switch can accommodate that, without having to change the probe z offset value.
Its been 4 years, will be cool to see a redo with current offerings
I'm officially finished with 3d/bl touches...they're both garbage, so yeah I'd like to see a 2021 sensor showdown myself 🙂
@@MAGA_Patriot2024 They really are garbage. for me after a long journey I came back to the source. end stop prob - klicky, the simpler the better
@@slimanus8m its been 5 years now
@@mynameisdex8785 Damn
@@mynameisdex8785 Ya....Now its official, just use Klicky or even Unklicky. it's simple cheap and accurate and cool
I think you did the BLTOUCH a disservice, Tom. While the other sensors perform equally well in any position, such as your horizontal position in the test fixture, the BLTOUCH is designed to work vertically. When put in the horizontal position, the sensor pin and magnet must overcome the additional friction of sliding along the bore of the guiding hole. This can lead to inconsistent measurements due to friction and grabbing. I consistently get average variation in
readings around 0.015 mm
This!. The BLtouch is probably the best sensor on the market when used properly. It doesn't care what your build surface is and once your offset is determined you never have to worry about bed leveling or adjusting anything to do with the Z axis again. I routinely start a print and walk away, and expect it to come out perfect, and it does. The autoleveling is done once the bed is up to temperature, then the nozzle wipes across a brass brush, and quickly moves to the bed and starts printing. The BLTouch is an awesome bit of kit.
0.015mm is a lot of deviation
I want to address something I've been seeing floating around the internet regarding the inductive/capacitive probes. People keep saying you need a 12 V to 5V voltage divider on the output. This is partially wrong, and may, in fact, introduce more errors in your bed leveling. The sensors do absolutely need to be run from 12 volts to achieve their rated specs, but if you are careful to buy an NPN type sensor, you can simply plug the output directly into the Ramps input pin. This sensors are what is called "open collector drain" output. It means that it doesn't provide an output voltage when trigged, rather it pulls the signal provided to it to ground. The Arduino/Ramps board has internal 20 kohm pull up resistors on all of its pins (enabled in Configurations.h). This pull up provides 5 volts to the output pin of the sensor, when the sensor triggers, it pulls that 5 volt signal to ground. If you use a voltage divider, you might reduce the 5 volts enough to cause unreliable switching in the Arduino. PNP type = needs voltage divider. NPN type = do not use voltage divider.
+Thomas Sanladerer Great video! Aluminum tape definitely works though! I have used it multiple times, amd we also use it reliably at our Makerspace. There are different types of aluminum tape however. It looks like you are using the "metalized" type that is similar to Mylar. That stuff will not work. You need actual aluminum tape. The metalized type isn't very conductive. Actual Aluminum tape is basically just like aluminum foil with an adhesive backing. The only thing you have to watch out for is the adhesive. Alot of aluminum tape has a low temp adhesive and will start peeling up at around 50°C, but you can find some that has a high temp adhesive which is what we use under our PEI at the Maker Space.
You can tell by the video that it's the wrong kind of aluminum tape. Actual aluminum tape has a dull surface to it, and it is much thicker as well. Basically the tape you tested is just plastic tape with a small ammount of aluminum vapor deposited on the surface. Other than that, Great video!
Agreed. I have had great results with aluminum tape on glass beds!
I've used copper tape in the past on glass, that worked pretty well as well.
Had minor problems with some Aluminum tapes and inductive sensors due to reduced sensing distances that I didn't like quite as well, found copper tape to be far better. But either works great.
In fact on my setup(8mm inductive @12v) copper has better sensing distance than the aluminum heatbed(My printer crashes on autolevel if I leave the glass off and it tries to sense the aluminum sheet)
Those here who use copper/aluminium tape under 3 or 4mm glass: What is your sensing distance? I put the tape on top and just don't print in the very corners as 1mm or so above the glass is too close for me with the tape under it.
I've been using a piece of heavy duty aluminum foil between my heated bed and glass for almost a year - with a 8mm inductive sensor it works great. It worked with a 4mm sensor as well - but was a bit too close for my tastes and Marlin's probe test seemed to show the 8mm was about the same for accuracy so I've stuck with it and been very happy.
I think one of the things you have to remember is that the BLTouch is an all-in-one solution for bed leveling; it won’t interfere with your nozzle at all because of its retraction. That retraction most likely adds a significant wobble.
If the tests were conducted as in the video , what do you make of Antcap's instructions regarding how the BLTouch must be mounted ?
The manufacturer's website for the BLTouch clearly states this: if the sensor is mounted horizontally it WILL give wrong results.
They don't equivocate. It is a crystal clear stipulation. It is underlined even . Would you care to comment ?
@@Traitorman..Proverbs26.11 except it is not just an electronic device . It is an electromechanical device and it is purpose designed to work mounted vertically . My kettle is a simple electronic device , it won't work as intended if I run it on its side or upside down.
@@Traitorman..Proverbs26.11 i take your point . But my inquiry is more to do with the method used to derive a conclusion , rather than the merits of this or any other device evaluated in the test. Manufacturer says this device X is designed and only works when used using method Y . Testing is done using method K , results turn out to be suboptimal . Why are the results suboptimal ? In truth we don't know ,. It may well be the product is unreliable but testing by using method K is not the way to find out. Over and out.
Yeah he should have tilted it...
If I'd design a device like this small I'd surely factor the gravity whether I'd use a spring to push the pin out or not (as it happens I'm not a flat-earther, I "believe" in gravity). Probably the pin is pulled in by a coil (with the ferromagnetic pin acting as a core). Because it needs precision, the spring, if there is one, should be weak, but the trigger point will be more influenced by the sensor orientation. I guess you could make it switch just by shaking it in the hand. To be able to ignore the gravity direction (and to have repeatability no matter the sensor orientation), the spring should be stronger, but, in this case, the precision will go away, especially with microsteppping. Factor in the uneven friction, which can be significant for a such small device and the need to keep the price small and you'll have an answer.
I don't own this small guy (BLTouch) and I didn't check the datasheet, but your observation is perfectly valid. And the BLTouch test is not valid.
Also the other mechanical sensor results aren't valid either because he's just testing the switch itself when to actually use it you'd need a mechanism to remove it to actually print.
When I was working on the auto-alignment at Type A Machines, I was very surprised at the unsolvable nature of the auto-alignment problem. There's essentially no way to get the desired flatness when combining the standard deviation of the sensor, with the rated flatness of aluminum, and the thermal expansion when heating to over 80C. You could conceivably do it with steel, but that has other challenges from the weight and cost of facing. Glass is really the only material we could find with below +/- 50 um flatness and dimensional stability when heated (we even managed to find some with +/- 0.3 um).
Really the solution is to crowd source some magnetic glass, minimum order is 5 tons and works with induction.
I'm game, magnetic glass ftw
just epoxy glue a steel sheet to a piece of glass
Is this going to be the sensor version of Fillaween? ... Sensorween?
你內部人員幹嘛
I know this video is over a year old at this point so I hope this is still relevant.
He tested all of these sensors horizontally. The BLTouch specifically states NOT to use it that way. It needs to be hung vertically as it would be mounted on a printer.
I've used a mechanical switch with manual leveling, a mechanical switch that flips up with a servo, capacitive sensors, inductive sensors, glass beds, PEI sheets, Zebra Plate from PRINTinZ, aluminum beds, and even tool steel beds. I've tried a total of 15 different sensors and 11 different beds in my few years of 3D printing. NONE of them were as accurate as simply using the BLTouch. When it is installed correctly, it just works flawlessly. Best of all it doesn't care one bit what surface you have, it will work on anything.
I think it deserves a re-test.
It has almost no deviation on his tests, maybe 3 micron, which is next to nothing. He also states that it doesn't care about the surface material. So actually even in this horizontal test it comes out as (one of) the best choices regardless of where you want to print on.
I never thought about using such sensors for measuring the bed level. At work I use mostly inductive ones but just for checking if there is an object or not. When I saw your video about the Prusa i3MK3 and its autoleveling I had doubts about the precision, but your video here has told me better. Thank you.
Tom. You pretty much nailed this one....also you mentioned that capacitive sensors are thrown off by humidity...they are actually the instrument they use to sense humidity.
This was awesome. Finally a proper comparsion between the different sensor types. Thanks a lot for your effort!
I would love to see this video updated to include Ultrasonic sensors, and name brand inductance sensors like those made by Osram up to say 16mm sensing distance. That being said, this video is so helpful. Thank you for making it.
ultrasonic too hard to work at small distance, basically time of flight is sooooo short electronics is not fast enough to process it. if you have at least 10cm distance then there is enough time to do calculation at reasonable precision yet you need to run higher frequencies. We tried to do auto focus device at 25mm distance even there we had to give up on ultrasonic sensors.
Can you use an inductive sensor with the removable magnetic plate on the table?
I don't know where you're getting your sensors but I use 1 strip of aluminum tape under glass. Works like a charm. I used it as a retrofit onto the printrbot simple metal and it worked better than with the aluminum bed.
newbie questions:
1) why isn't any using ultrasonic sensors ?
2) do high end printers use laser/lidar ?
thanks for the video, very informative!
1) 2) there must be distance for both of them. None of them will allow you to notice when the nozzle < 1cm. I guess there might be a workaround with offsets though when 5/10 centimeter or something like that.
Ultrasonic sensors are not precise enough to do the job.
Lidar is a process where an infared laser light creates a kind of radar around it. 3d Printers are only trying to measure distance in one direction. It is much simpliler and more practical to not use lidar. Ultrasonics are another radar type with help of a servo, Most radar like sensors are kind of inacurate but still acurate enoguh for their use cases like on a car or a plane. Where 3d printers are looking for accuracies of up to micrometers.
Always learning,
Aidan Villacampa
Prusa uses a laser to detect stoppage in their filament sensor. You can get them on Aliexpress
Are there any sensors that can map out the Z axis lead screws intolerances?
I feel like I've been in a time capsule. I got an early MakerBot CNC (#180) in 2009-ish, and was printing 3mm ABS on a raft on Kapton tape, using a .37mm layer height and no fans or heated beds. I woke up in 2021 receiving a Prusa Mini+ that prints directly on a magnetically attached and heated bed, using 50 micron layer height if I so desire, and supporting PLA, PETG and a plethora of other materials out of the box. In the old times, I tried using an optical mouse sensor for auto-leveling using focus. It actually worked with the sensor 1 mm from the bed, but I wanted something more like 10mm from the bed and never got the optics to work correctly. The idea was that the optical mouse sensor not only sensed the height, but also could read markings on the bed, or a printed sheet attached to it both for calibration precision and for communicating what to print. I never got to finish this project, but it seems like it still might be worth while: the inductive SuperPINDA doesn't even provide much headroom. Does anybody here have experience using optical focusing for Z height calibration?
You measured mostly repeatability, and mostly ignored system accuracy due to heating/cooling.
Excellent video, great charts.
Should have had an external digital DTI measure the setups actual position, logging, and dwelled (paused) after contact on the probe.
Then the DTI log would show where the moving piece actually was at probe contact, vs the start position when all was cold.
Likewise, the triggering circuit for probe hit is critical.
I did a lot of work on this, 8 years ago, on testing for lathe spindle index sensors, and we proved conclusively that sensors will give very fuzzy signals, that vary with temp/speed/luck.
A sharp triggering circuit, and a sensor tuned to give a crisp response, will be about 100x more accurate on a range of speeds vs a typical probe "hit".
I also saw that optical sensors will repeat to about 2 microns, with very simple basic cheap sensors.
Thanks for your videos. I have experienced difficulties with sensors. After a few consecutive prints, the levelling of the bed was not accurate, but was accurate again the day after. I now make the levelling when the bed is hot, but the problem still exists. I believe that the sensor close to the bed and the head warms up little by little, and the temperature of the sensor may have some effect of the measurement.
I have a question about the inductive sensors... How much 'material' do they need below and around them and at what point does it make a difference? For instance: If I trigger right on the edge of my aluminium plate it triggers lower then when probed in the middle of my plate. Does thickness play a huge role? Do they trigger higher when there is a bearing holder right below the sensing point? How thick does the aluminium need to be to not have that influence...
one thing you're missing are FSRs, force sensing resistors. i use them on my delta which has a glass bed over an aluminum heat spreader.
they seem to be very repeatable but only above 0.13mm deviation, any less than that and smoothieware's autocalibration gets upset
I too use FSR's with Smoothie on my delta. I like them a lot, though they have their own drawbacks too.
How do you feel about auto levelling? I personally don't like the idea of the Z axis having to move during a layer print. If I'm worried I just use a raft, which will end up levelling before the actual model prints. What I really want to see is 3 servos to level the bed corners.
Servos are just so unstable. What you want is the thumbscrew on top and having a hook for the nozzle to turn it. *g*
HenryLoenwind no idea what crazy setup you're envisioning but I guess it's not the one I was... I use servo in its loosest term: any motor hooked up to a potentiometer to increase positional accuracy, not as in your hobby king swivel arm 180° ones. As such, a small motor attached to the thumbscrew so it works as a linear actuator and a linear potentiometer hooked to that setup for positional feedback. Doesn't seem too ludicrous.
You were suggesting using the nozzle to turn a thumbscrew? That grates against my engineering sensibilities quite badly.
+HenryLoenwind
Oh man, the mental image you just gave me of a printer spinning its nozzle around a hooked screw to 'adjust' itself before it feels comfortable enough to start producing a part is hilarious to me, for some reason.
Guess you missed the G at the end. He was joking. LOL!
I thought it particularly funny a guy with "Mirth" in his name would miss the joke. :-D
My team is actually working on a printer for the market with all best stuff available, and that includes 3 steppers for Z axis for REAL bed leveling, not some sort of lame workaround. ;) Fast hotbed (0-110C in 25 seconds), 300x300x450 build volume. Won't be cheap though. Good stuff is never cheap :)
Usually there is a spec sheet prescribing optimal materials and thickness with respect to frequency (typically a few mils for ferrous and 2-10x thicker for nonferrous). The relevant parameters are permeability and resistivity of the material. Ferrous materials and sensors generally can give higher resolution with larger sensors, and non-ferrous gives better resolution with very small sensors (even though typically smaller sensors give a shorter range), but there are universal sensors that have an equal correction factor for either.
Generally ferrous sensors would probably work best in this application, and Generally target size should be 1-3 times the sensor diameter. Also, in terms of layered copper/alum tape, remember that you are isolating the layers electrically, so the induced eddy currents will be smaller (just like transformer laminations)… meaning you may need more layers of tape than you would expect.
If I were adding a proximity sensor after the fact, I would get a medium-distance ferrous sensor, tape ~1mm thick steel disks to the bottom of the bed at the sensor points, fiddle with the distance, and call it a day.
Good video.
I have thought about switching to inductive sensor but now I just think I can keep the microswitch without the lever.
Another one to try is the piezo force sensor. Mount it in your bed support or (as I did) in your hot-end mount on the carriage and it registers contact of the nozzle to the bed. Zero probe offsets in X, Y and Z, change nozzle and all you have to do is run the auto-level. Super convenient. Precision Piezo do a good rig.
This is interesting. I see that microswitch w/o lever SD is about 1 um. Same as for inductive sensors. What is the point of using Bl touch or inductiv sensors if once can just put a microswitch button down on the print head and do autoleveling with it? but how to put it higher that the nozzle...
Thank you for this comparison! We just doing the same for a customer and we were asked this question very often as we do a lot of printer customizing.
For the mini-IR probe to be used on glass, the instructions say to put a black matte backing (black paper) behind it, or to paint the surface behind it matte black with high temp BBQ paint. A reflective surface behind it like aluminum will give the kind of results you saw in your tests.
Tony, see my clone of Davids mini IR, community.robo3d.com/index.php?threads/differential-ir-height-sensor-attemptin-clone-aint-sure-of-success-now-stage-10.6601/ ............Yes, you correct.....paint back of glass flat black.......Jimmy
I've been saying the same thing. This test was worst possible scenario for IR probes and IR probes only. I wish it was done properly.
Thanks for all that testing but now I want to know which probe is best for the Scoovo X9H.
It has Kapton tape directly stuck on a glass bed with the silicon heating pad just under it.
Board: RAMBo
Firmware: Marlin
Can you redo the tests but use the BLT touch the way it supposed to be vertically mounted not horizontally
What would the point be? He flat out told you it was done sideways to remove backlash from the equation and limit the results to just the component . Turning them upright wont change how the devices reacted mechanically one bit .
@@wind5250 and apparently you didn't read the instructions for the bill touch it supposed to be vertically standing not horizontally to work properlyso if you want to test something the way it was made to be tested and used that's the way you do it not for non-science a backlash there's no backlash when there's up and down
@@mathewphillips4185 not only did i read the instructions i own one. Laying it on it's side is just as valid as standing it up. The fact his results are within spec as well as repeatable , and comparable to other reviews more than demonstrates this .
@@wind5250 you read the instructions but apparently didn't follow them (and are misusing the equipment you own, but that's your choice). It's simple physics to demonstrate that there is a mechanical difference in how the probe behaves when it is vertical vs. horizontal:
When vertical, gravity acts on the spring to pull it down and keep it in its rest position. When the probe hits the surface, it can cleanly move upward until it can trigger its Hall sensor. When horizontal, not only is gravity no longer aligning the spring correctly, but there is additional friction resisting the movement of the probe (thus causing the probe to move fractionally less for the same amount of deflection). When the probe contacts a surface horizontally, there is no force preventing the probe from deflecting sideways ten+ microns before triggering the Hall sensor, leading to a loss of precision.
If using your equipment like this works for you, that's great, but it's objectively incorrect to say that orientation doesn't have an effect on the BLTouch and other precision equipment.
@@TROPtastic You took all that time to write a reply but obviously not enough to actually comprehend before hand . First of all i never said how i mounted the device let alone i mounted it sideways. What i said was it would make no difference to repeat the test upright because the results are within spec and repeatable which they are .
You are literally arguing that the device will perform better than the manufactures tell you it will by turning it right side up.
Anyone who actually uses this device knows they give invalid readings after time the only valid questions would be what version this is and was this one new or used .
out of all the sensors that you tested what one would you recommend to use on an aluminum bed with 3-4mm glass
i guess you can't go wrong with the bl touch if you print on glass
Why do you need a leveling sensor on glass aren't they flat?
@@chloemcholoe3280 The glass (print bed) will be a flat piece of glass. However, it is then mounted inside a mechanical device. If one edge is mounted lower than the opposite edge then your first layer of 3d printing will not adhere well to the glass. The print bed must be leveled to ensure that the 3d print head glides over the whole print bed at the same height before a 3d print begins. Then the 3d printer will reliably 3d print the first layer and subsequent layers. This leveling can be done manually, with no automated sensors, or leveling can be done with automation using the kinds of sensors tested.
@@paull1316 yeah. my point was the reason I for these probes in my opinion is for fixing warpage. with glass you can just like live adjust the 4 corners as it's printing and it takes a few seconds really
@@chloemcholoe3280 - glass can be warped or bowed if not made correclty. Also, glass isn't the only height variable. its possible that the gantry rail that the hot end rides on can be bowed.. which may change the height of the nozzle as it moves back and forth.
Clear, concise, metrologically accurate and empirically awesome. Legend.
Informative as always. I use a LJ12A-4-Z/BY with an LM7805 VR on the output this gives a steady 5 volt trigger signal.
If you increase the input voltage does it does it strengthen the sensing distance.
This is awesome! Also fun fact: I use an aluminum mk3 heatbed with a 3/32 inch (2.38 mm) sheet of glass AND blue tape. The 8 mm inductive sensor triggers just fine for me thankfully.
i use inductive 4mm and the bed is made from 2 sheets of glass (3mm) and graph foil (0.2mm) in between and works great.
Very happy with David Crocker's differential IR sensor and a sheet of Printbite.
Especially good description of what standard deviation means in this situation. Gut gemacht!
Great info, thanks Tom. I recently installed David Crocker’s IR sensor on my Prusa i3 box frame, which uses a 3mm glass bed and a red Mk2 PCB heated bed, inked black with a permanent marker in the sensor probing areas.
After watching your video, I tweaked Marlin so that G30 would output the trigger height to 3 decimal places (1 micron resolution). I turned on my printer and made 46 measurements with G30 and got an s.d. of 1.4 microns. I noticed a trend in the data, presumably due to temperature drift somewhere in the system (probably the steppers warming up my crappy M5 threaded rods so the trigger point appeared to get lower with time). So I did another 34 measurements and the s.d. was 0.8 microns, but still with an obvious trend.
I think these numbers are an order of magnitude better than you got with glass. Maybe it matters what is behind the glass?
I should also mention there was a thin layer of glue stick on the bed under the probing area from the last print. Also I have slightly modded my sensor board to increase the trigger height from about 2.7 mm to 3.2 mm by tweaking the angle of the outer LED using a hot-air rework station. This is so that it would clear the bulldog clips I use to hold the glass down so I could still retain my full 200x200 build area.
That's because, most likely, your bed surface is suitable for Crocker's IR sensor. The testing surfaces and setup in the video is stated as not suitable in the documentation. If you are running a glass plate on top of bare aluminum it is recommended to paint the aluminum matte black. I wish this test was done with the proper setup.
I don't use autolevel for couple reasons - I print on glass, and I can't afford (or justify the expense of) ball screws. I use an inductive sensor (LJ8A3-2-Z/BX-5V), as a fixed Z end stop switch, sensing a mild steel bolt head. Using a digital 'dial' gauge, I get repeatabilty of ~3µm delta (not standard deviation). That's with T8 lead screws and DRV8825 drivers, 32 microsteps, so 1.25µm per step. Not bad I think, for a modest outlay, and plenty good enough for 3d printing.
Mh for the LJ18A3-8-Z/BX I run it directly from the board without a voltage divider. Tried it first with your voltage divider approach but then the sensor didn't trigger at all. But running the sensor directly of the board it works fine (for me on a aluminum bed with BuildTak ^^)
Try the sharp with an offset. Ultrasonic sensors generally can't read values accurately below a certain valve, due to the reading times required for the sound wave. Try offsetting it and see if accuracy is better.
Hi, I use some lj12a3-4-z/bx on my printers and it triger on a glass plate with some almuminium foil sticked with rubber tape on it. Also supplied in 5V directly plug on my borads without any led or resistor.
Should've tested 3D touch as well, for example from the famous clone manufacturer Trianglelab.
3D Touch has a deviation about 3x worse than BLTouch.
if you are going to be looking at the Sharp IR sensor you may want to also take a look at the time-of-flight sensors, the VL53L0X and VL6180X
I have Omkon SN04-N inductive sensor. I use glass bed and have one layer of aluminum tape ON TOP of the glass where the sensor probes.
It works pretty well :)
I'm using an 8mm NPN output inductive probe, the same 8mm one in the video. Rather than using a voltage divider what I use is a diode instead. When off it puts out 12V and goes low on trigger. So you put the diode in series with the output with the cathode towards the probe to block it and make sure the pullup resistor on the input is enabled in the firmware. When the probe triggers it goes low and turns on the diode and pulls the input down to .6V which is good enough to be considered a low on the input. The diode will give a nice cleaner trigger to the input than a resistive voltage divider will and it's easier to wire and insulate, just solder in series and cover with heatshrink
I'm sensing nothing but a 10"x10" PCB heater (Sitting on cork to keep it flat and insulate it) with a 2mm thick piece of hardware store glass on top and the repeatability is near 100%. I always use it on a preheated bed and that seems to help repeatability. My only gripe is you have to recalibrate it in the firmware if you do any work on the hotend or X carriage but that's not often so it not a big deal since the rest of the time it's pretty much "plug and play" printing. Cheap effective upgrade IMO
I liked this video a lot, I simply wish the sensor I use (David Crockers IR Sensor) had a slightly deeper/more in depth review. I am given more confidence to continue using it, however, will no longer calibrate it with the heated bed on.
That is a variable I had not even thought twice of! I simply set the bed for 55° for my PolyMax PLA and calibrated it when it was done heating right before the print...Thank You for that!
for my scratch built reprap delta we used a simple conductive type, running 1 wire to the nozzle, and another to the aluminium bed, reeally simple and easy, and no need to worry about effector tilt
Would you please make a video explaining limitations of autoleveling? A lot of people seem to think it will compensate for misaligned axes (like when a dual motor Z axis loses motor sync and the X axis tilts).
@Thomas - And additional info for you: I've noticed a huge unreliabilty with my inductive sensor C-Lin P-802N (runs nicely at 5V) - first I thought it was caused by temperature differences caused by my huge high powered heat bed, but after a while I found that even smallest drops in the voltage of the printer control boards PSU makes sensing distance very unreliable (using a cheap chinese 12V 6A notebook-psu brick for the board+hotend). I've came to that conclusion after changing to a old and dirt cheap ATX psu as reliability got MUCH better but still got not perfect (bad quality "250W" ATX PSU). Now I'm using a 200W 12V halogen trafo, rectifier, added several very huge Elko capacitors (about 50k µF all together) and now sensing distance is +- 0.00Xmm reliable instead of +-~0.3mm!!! I heard that the BLTouch (and it's chines "3DTouch" clone) have similar problems.
After re-viewing this video again, I wondered why you tested all of the sensors on the same surface (aluminum) as the different types of sensors each work best on particular surfaces. For example the inductive sensors only work against a metal build surface such as flex sheets with PEI or PEX. The IR sensors work best with a black body, or no- reflective surface such as build tak, and poorly against aluminum and non etched glass. Capacitance probes need to be adjusted, but will work with numerous surfaces. They should perhaps be used with the bed heater on, and at less than 65C.
That test machine was brilliant! I built an i3 clone following your guide and this sort of thing is really great for developing upgrades. Thanks for being so thoughtful in the design and execution of the testing.
When you tested the inductive sensors you didn't take in account the heterogeneity of an aluminium bed.
While printing with my VORON I have experienced inconsistencies with inductive sensors and my PEI-painted Aluminium bed from Clever3D. Basically the trigger distance was consistent on the same spot (just like in your tests), but varied when probing a different spot... and you need to probe at least 3 distant spots.
Today I switched to the VORON 1.5 X carriage, which uses the hotend itself (mounted on a mechanical microswitch) as a probe and the situation is vastly improved because a microswitch isn't affected by materials and temperature.
EDIT: In theory this applies to IR probes too, as reflectivity may vary across the bed.
Really cool video! The idea of applying statistics touched base, true engineering style, trial and error!
Seeing as inductive probes can see through plastic/silicone, would it be sensible to put a silicone sock (or even a printed plastic cap) over the bottom of the inductive probe to reduce temperature effects? I'd be really interested to see if that helps.
How does Marlin deal with the measurements from the probe? Will it compute a plane with minimum distance to each point, or does it compute a non planar surface to deal with deformations of the bed or bending/wear of the linear supports carrying the print head.
The video was very informative. But I have to question your method of testing the inductive probes. The aluminum bed on printers with them are only around 6mm, not the large mass of aluminum you used. Could you rerun the tests using a 6mm aluminum plate and test the trigger height between probing the center, edge, and corner of the plate? In my use of an inductive probe, I have seen a difference in trigger height based on where the probe point is on the bed.
Edward Boston I may be crazy, but my inductive probe acted like it was "seeing" my steel bed carrier through my MK3 aluminum heated bed. Is that possible?
I doubt it, but you never know. I was seeing all sorts of inconsistency with the probe I was using that I gave up on it and went with a BL Touch. One issue I had was I have a PrintBite on my bed and with a 4mm probe, it had to be so close to the bed that it was almost at the same level as the nozzle.
Almost 2 years later now and I still adore my BLTouch. Even if it statistically or scientifically isn't the most accurate out there, as you say, it's 'more than good enough'. It's so rare to have a calibration fail.
Tom, you really should continue wit the Myth-busting line. I have been experimenting with sensors I have to say that your conclusions corroborate my experience 100%. Given mechanical switches with lever , although less precise than inductive, can be used with borosilicate glass, I will stick to those. Awesome video, congrats.
Did I miss the link to your spreadsheet with the measured data?
He posted it on a comment above: docs.google.com/spreadsheets/d/1QDtd-0IK79gme_f80Rw_PB-nIActKWJJJvvAYd4u2uM/edit#gid=0
Thank you :)
was looking for this and missed it. Browsing RUclips comments pays off(amazing!) Thanks!
Tom, if you retest the optical sensors, I would like to see it done with different color materials behind the glass (specifically black, white, red and peach- the common colors of heaters). Would also like to see how ambient IR light affects the repeatability, i.e. fluorescent lighting and sunlight. I had very mixed results with David Crocker's IR sensor during probing with sunlight coming in through the windows, for example, vs. probing in a dark room.
The IR sensor I make doesn't like bright sunlight (no clouds in front of the sun) shining directly on the bed and reflecting into the sensor. The current version 1.2 will flash the LED rapidly to warn you when it detects that. Otherwise, it isn't affected by ambient light. Incandescent light - especially halogen - affects some other types of IR sensor, but not mine.
I'd also like to know what material was behind the glass when Tom did his tests. The reason that glass and other transparent materials can cause problems for optical sensors is that you get 2 or 3 reflections: one from the front, one from the back, and possibly a third from whatever is behind the glass. We want the one from the front to be stronger than the others, which is why we recommend a black surface behind the glass.
Have you try the membrane film based zprobe (basically just like a membrane keyboard/contact switch)? I find it is the best zprobe for delta printer as it can be easily mounted directly under the nozzle to give the best on-points reading that a delta auto calibration needs (no zprobe offsets), without being affected by heavy trigger force that could potentially deform the belts/pivot points etc.
where is Prusa i3 MK2 cloned part 2 :(
I want to build my first cheap 3d printer
HYPE!
Runder Caster go to microcenter! they have a Prusa clone from wanhoa for $299! works amazing for the price with decent print volume 200*200*180. I'm trying hard not to buy a second one.
Building printer your self is much cheaper and you will learn how it works, so when something breaks you know what to replace
I already ordered all of parts required to build clone of prusa for around 80$(not including frame, I will build it my self)
woops sorry misread your post as "get a 3D printer" $299 ($399 online elsewhere) was the cheapest I'd seen for fully assembled all-metal printer with that build volume just trying to help out.
Enjoyed the video. I've actually used the thicker gauge of "Duct Repair Foil tape" by sticking it to the top of the glass sheet and then putting a sheet of BuildTak on top. Maybe that's not aluminium? Anyway, my cheap sensor saw it.
I'd be interested in your review of the piezo electric z level sensor, it looks super interesting to me. It has a bed option and a hotend option, it's always there and has no XY offsets.
How are you only at 67K subscribers? Your videos are so good and the editing lighting etc is amazing! I wish you lots of success Thomas. I really enjoy every single video that you make.
He could get millions of subscribers from the FNL (GDR) which never learned english.
Tom's videos are great and have amazing production value but how many 3D printer enthusiasts do you think are in the world? I imagine 67k people is a sizeable proportion of them.
Touché, but also lots of people that are interested in 3d printing don't have to be enthusiasts. Like you said though his production quality is probably some of the best on RUclips, and that is not an exageration. Many channels 10 hell even 100 times his size can learn a thing or two from him!
67k is quite a small subsection of 3d printing enthusiasts. Talk to Lulzbot and Ultimaker about their sale figures. Heck, Prusa and his company are shipping 3,000 printers a month, and that's only because that is the limit at what they can produce right now, giving new orders a 7 week lead time.
So this got me thinking what is the size of the global hobby 3d printing market? There's plenty of data on additive manufacturing market size but that's not people buying prusa i3 mkII's.
Your videos are all excellent, but this one is superb! We spent so much effort learning this on our own... at Kikai Labs we use a capacitive sensor, take 16 measurements prior to starting each print job and level the bed automatically. It works great. We do calibrate the sensor first using three different bed temperatures, as it does matter as you pointed out. Interesting observation about the humidity, though... I used capacitive so that it would measure the glass surface, and we use a mirror instead of plain glass, and get better results. Also we found that the smallest the measuring distance, the more accurate it is, so we measure from 2mm away using a 12mm sensor.
Y que le paso a Kikai Labs?
You should have tried steel foil. I bought some SS foil off ebay, a single layer of fractional mm thick tape does trigger a 12mm inductive sensor, but NOT though glass. Maybe on top of glass covered with kapton tape?
Wondering if instead of aluminum tape, if using a quarter or half a zinc coated, or stainless steel washer, sanded flat and to a common thickness, and glued to "sensor points" on the corners, or a known distance from a corner, would be a workable solution for glass build plates and inductive sensors. One might have to go to a fender washer for enough ferrous material to sense, but if there is a way to tell Cura or your slicer that those locations are off limits for printing, it might be workable.
The advantage I see is that most of us have access to washers, if you've adjusted an inductive sensor for an aluminum bed, you may be familiar with having to do other physical adjustments already.
Down side would be that you wouldn't want to do grid leveling for this, unless you could etch your glass to drop such washers into the surface, and I'm not thinking that's a great idea.
Unknown is how large a washer you would have to use to get reliable results from an inductive sensor.
great video! cool rig, shows the power of rapid prototyping. been thinking about Auto leveling, I have a delta that uses pressure pads, would be great to see how well it stacks up, down side is Auto leveling is tapping printer head into the bed every time.
David Crocker designed his sensor to use black paper backed glass, however I don't see any test of that case.
Wow love the detail and different perspectives covered in this video. I'm a sucker for this sort of data. If inductive sensors have their detection range halved, and there is a sheet of window glass (2.38mm thick) on top of the bed, doesn't that mean that both 2mm and 4mm inductive sensors are right out?
I'd love to print ABS right on the aluminum but nothing sticks to it without a carefully maintained pile of glop (glue/slurry), where glass works for weeks with a single light hairspray application.
I wish your test apparatus also used a layer of glass, typically found on CR-10x's. If the sensor needs to be too close to the glass so as to interfere with prints during printing, then that is a fail. Please account for sensing distance to the detected object.
Have you looked at a sonic sensor? Like the ones that come in the Arduino kits. Can it be adapted to measure and trigger at the distance it is mounted, at on the print head? When I played with one some time ago, It seemed very accurate for 50mm to 800mm.
You are trying to set head position to a fraction of a layer height, so about 0.02mm say. Those sonar sensors have nowhere near that resolution.
The BLTouch manual specifically states the sensor must be run vertically. Since your test rig is horizontal, the results are suspect. It would be good to rerun the BLTouch test with it held vertically.
Many years later and the BLTouch and the clones are the most used. Inductive requires the metal to be the exact same accross the entire bed surface, so it's out in most cases. Of course now we have Lidar sensors. Sticking with my genuine BLTouch setups for now. They just work.
Here's a question, with the inductive sensor, does the voltage range matter? ie does the sensor (say, a 6-36v sensor) work the same at 6v, as it does at 36v?
The Sharp detectors take 16.5 mSec to take a measurement and output that value. Or put another way, the analog or digital output changes every 16.5 milli second and the output stays the same in-between its readings.
any chance we could see a version of this test with some piezo action too?
Thanks for your video, now I can comfortably purchase an induction sensor with the knowledge I will likely have to give up my glass bed. I appreciate all the testing you did!
Great, informative videos. Thank you. I was wondering if you tested the BLTouch horizontally or vertically? I think that its accuracy is affected by gravity and would benefit from a vertical test. I agree that it is a good alternative for glass probing.
A coil-operated pin this small and light should not be influenced by gravity at all. The testing method is perfectly acceptable in this case.
@@pellin-unleashthebiker3101 not when you're dealing with micron-level precision. I calibrate measurement equipment to this level as part of my job, and misusing equipment like this is a total non-starter if I want something to perform accurately.
@@TROPtastic did you look at the precision of the bltouch horizontally in this video? It is only some microns, so still perfect. So the conclusion is it really does not matter in this case. For something else it may, but not for a simple 3d printer.
FYI, you tested the BLTouch in the wrong orientation. I tested mine thoroughly at multiple homing speeds and standard deviation was 0.01mm with the occasional one that that was +/- 0.02mm, on all but really fast homing speeds.
I now do a two step homing with it, once at 1500mm/m, and then a slow home at 100mm/m from ~2mm of the bed.
For the longest time, when I was running my Simple Metal with a glass build plate, I had to use aluminum tape to get the inductive probe to fire. I assure you it 100% worked. There are different thicknesses of aluminum tape, I suspect that was your problem here.
Hello. Where can we read the results please? I am very interested by mecanical switch results (with and without lever)
As I understand, at 7:24; mecanical without lever is more precise than BLTouch ? cool!!
The only reason I moved from an inductive sensor to David Crocker's IR sensor is because of the bed. If the thickness of the bed varies, or there are holes in it to reduce weight, the induction sensor will trigger at a different height to more/less material being on the bed in one location.
Awesome test! Very methodical tests. I have the cap sense and have noticed the heat issues. I think I'll switch to inductive.
I would like to try a glass bed over the aluminum lower plate. I wonder if the the longer range inductive sensor would be practical at detecting the aluminum glass combo.
Great video Tom. I have two related questions. Since you agree that 12V is far more precise than 5V would 30V be even better? And if so can you use an external power supply to power the sensor and feed the result into the board without damaging it?
Your idea seems correct, but no need for an external power supply, you could use a "step up" www.amazon.com/Solu-Adjustable-Converter-3-5-35v-Voltage/dp/B00VA0GRFG/ref=sr_1_3?ie=UTF8&qid=1490647751&sr=8-3&keywords=Step%2Bup%2B5%2Bto%2B36V&th=1
And then divide the reading with capacitors
Cool comparison. I was looking for a sensor to measure distance for my research project. So this helped me to understand the basics of the sensors. Thank you for that. Also is it possible to have the part list for your test setup? It will be really useful.
I know this is an old video, but I hope that you still read comments. Tom, How do you connect a simple 2-wire switch to the mobo for the board to know when it has closed the circuit?
A quick vid would be nice.
The exact procedure really depends on the firmware used, but the steps are typically:
Configure the pin you want to use as an input in your firmware
Enable pull-up for the pin in software or add a physical 10k resistor from the microcontroller's positive supply (3.3V or 5V) to the pin
Connect one pole of the switch to the input pin, and the other to ground.
This way, the input pin will be high as long as it's not pressed and low when pressed.
prusa's pindais always the smallest of the group :D. Hey Tom how about plastic cube inductive senders? SN04-4, TL-Q5MC1. They become quite popular due to a low price and compact size. I've tried them but they seem to have a higher temperature deviation compared to round metal variants.
Re-viewed this video. It occurred to me that an NPN NO sensor has an open collector output to ground (V-). So it might be possible to run the sensor at 12-24vdc power, but have the output switch a 5v pull up resistor to ground thus giving a 5v negative true logic output. OR it could switch an opto isolator. Either way, you get a 5v logic output, but might need to invert the logic in software. Marlin probably provides for this anyway.
How do i use a microswitch for the auto leveling? I mean where should i put it, so it is not interfering with the nozzle and mess up the print?
It seems a good option for me. I have glass bed on top of an aluminum sheet... (DIY)
Why don't they sell a piezo or ruby sensor?
I mean the proffesional CNC machines use Ruby tips with light refraction for sensing, and the price of synthetic ruby is actually quite affordable.
The piezzo idea is to just to let it act like a microphone hearing when it hits the surface.
Would the inductive sensors work better on the magnetic beds, or indeed with magnetic tape under the bed in the positions you are probing?
would it not be best to combine different sensor types in one device, for example inductive and contact, and measure the deviation of these for error analyses?
How about a extruder comparison test? or better, how about a linear bearing comparison test? I am not a huge fan of Prusa's linear bearings but would love to know some numbers of if Igus or others are really better.
Jared Farnum this would be very interesting for sure
I would not use cylindrical rails at all. I'd stay with linear slides.
Some time ago I built a DIY heated bed to my Printrbot Simple Metal. In order to get the sensor to detect the bed through the glass, I had to put a sheet of 1 mm galvanised steel sheet under it. But now, the sensor almost touches the surface of 3mm thick borosilicate glass. Not really useable. I could not find borosilicate glass less than 3 mm thick. I read that plain glass can withstand a certain amount of heating and cooling as long as it happens slowly. But how slowly?
I decided that glass of the type used in picture frames was cheap enough for an experiment and I bought a couple of 200mm square glass frames from a bargain store. This glass, being only 1.5 mm works reliably with the built-in heating setting (I did not have to make the glass heat more slowly) though I must warn that, since I only use PLA, this setup has never been tested above 60c!
Also, borosilicate glass can withstand some downward pressure (when things go slightly wrong) - but picture frame glass cracks immediately. I lost both in the experiment, but have had 6 perfect prints off the third, with one coat of Magigoo on the glass.
Necro, but thanks a billion for making this video. Would be interested to see what new sensors are out there, and learning more about the LIDAR from the Bambu Lab X1C
Assuming the data collected is accurate, in order to make probe comparisons, large tolerances must be added to inductive probes that include the build plate tolerance stack for non-conductive top sheets (adhesive, PEI, etc...) . Also the BL Touch is intended to operate vertically, more friction is introduced horizontally. Once all this is considered and included, the BL Touch will compare MUCH better, if not the best. Also, if tossing on a thick G10 build plate for printing Nylon ... only the BL Touch or a micro switch can accommodate that, without having to change the probe z offset value.